/* ============================================================
   下一代网络安全新形态教材 · 官网样式
   清华大学出版社 × 极牛众星计划
   设计基调：深空蓝 + 清华紫 + 科技青
   ============================================================ */

/* ---------- 设计令牌 ---------- */
:root {
  --bg-deep: #04060f;
  --bg:      #080d1f;
  --bg-raise:#0d1531;
  --card:    rgba(255, 255, 255, .04);
  --card-2:  rgba(255, 255, 255, .06);
  --line:    rgba(148, 163, 196, .14);
  --line-strong: rgba(157, 78, 221, .35);

  --text: #e6ecfa;
  --dim:  #96a3c6;
  --faint:#5f6c8f;

  --purple: #9d4edd;
  --purple-deep: #6d28d9;
  --cyan:   #3ec6f3;
  --gold:   #e7c26b;

  --grad: linear-gradient(120deg, var(--purple-deep), var(--purple) 55%, var(--cyan));
  --grad-text: linear-gradient(100deg, #c77dff, #9d4edd 45%, #4fc9f5);

  --radius: 14px;
  --radius-lg: 20px;
  --nav-h: 72px;
  --wrap: 1200px;

  --font: "Source Han Sans SC", "Noto Sans CJK SC", "PingFang SC",
          "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;
}

/* ---------- 基础 ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 8px);
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

::selection { background: rgba(157, 78, 221, .4); }

.wrap {
  width: min(var(--wrap), 100% - 48px);
  margin-inline: auto;
}

/* 全局背景氛围：紫光晕 + 网格 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  background:
    radial-gradient(900px 500px at 85% -5%, rgba(109, 40, 217, .22), transparent 60%),
    radial-gradient(800px 500px at -10% 30%, rgba(62, 198, 243, .10), transparent 60%),
    radial-gradient(900px 600px at 110% 75%, rgba(109, 40, 217, .12), transparent 60%),
    var(--bg);
}

/* ---------- 顶部导航 ---------- */
.nav {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  transition: background .35s, box-shadow .35s, border-color .35s;
  border-bottom: 1px solid transparent;
}
.nav.scrolled {
  background: rgba(6, 9, 22, .82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom-color: var(--line);
  box-shadow: 0 8px 32px rgba(0, 0, 0, .35);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  letter-spacing: .02em;
  white-space: nowrap;
}
.brand-logo {
  width: 38px;
  height: 38px;
  flex: none;
  border-radius: 10px;
  display: grid;
  place-items: center;
  background: var(--grad);
  box-shadow: 0 4px 18px rgba(109, 40, 217, .45);
}
.brand-logo svg { width: 22px; height: 22px; }
.brand small {
  display: block;
  font-size: 11px;
  font-weight: 400;
  color: var(--dim);
  letter-spacing: .14em;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
}
.nav-links a {
  padding: 8px 14px;
  font-size: 15px;
  color: var(--dim);
  border-radius: 8px;
  transition: color .25s, background .25s;
}
.nav-links a:hover { color: var(--text); background: var(--card-2); }
.nav-links a.active {
  color: var(--text);
  background: linear-gradient(120deg, rgba(109,40,217,.25), rgba(62,198,243,.12));
}

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--card);
  cursor: pointer;
  padding: 10px;
}
.nav-toggle span {
  display: block;
  height: 2px;
  margin: 5px 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform .3s, opacity .3s;
}
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: calc(var(--nav-h) + 48px) 0 0;
  overflow: hidden;
}
#hero-canvas {
  position: absolute;
  inset: 0;
  z-index: -1;
  width: 100%;
  height: 100%;
}
.hero::after { /* 底部渐隐衔接 */
  content: "";
  position: absolute;
  inset: auto 0 0 0;
  height: 160px;
  background: linear-gradient(to bottom, transparent, var(--bg));
  pointer-events: none;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 7px 16px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: rgba(109, 40, 217, .12);
  font-size: 13.5px;
  letter-spacing: .06em;
  color: #cdb4f5;
  width: fit-content;
}
.hero-badge i {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 10px var(--cyan);
  animation: pulse 2.2s infinite;
}
@keyframes pulse { 50% { opacity: .35; } }

.hero h1 {
  margin-top: 26px;
  font-size: clamp(38px, 6.2vw, 76px);
  line-height: 1.16;
  font-weight: 900;
  letter-spacing: .02em;
}
.hero h1 .grad {
  background: var(--grad-text);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero-sub {
  margin-top: 20px;
  max-width: 640px;
  font-size: clamp(15px, 1.6vw, 18px);
  color: var(--dim);
}
.hero-cta {
  margin-top: 40px;
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 30px;
  border-radius: 12px;
  font-size: 16px;
  font-weight: 600;
  letter-spacing: .04em;
  transition: transform .25s, box-shadow .25s, background .25s, border-color .25s;
}
.btn-primary {
  background: var(--grad);
  color: #fff;
  box-shadow: 0 8px 28px rgba(109, 40, 217, .4);
}
.btn-primary:hover { transform: translateY(-3px); box-shadow: 0 14px 36px rgba(109, 40, 217, .55); }
.btn-ghost {
  border: 1px solid var(--line-strong);
  color: var(--text);
  background: rgba(255, 255, 255, .03);
}
.btn-ghost:hover { transform: translateY(-3px); border-color: var(--purple); background: rgba(109, 40, 217, .12); }
.btn svg { width: 17px; height: 17px; }

/* Hero 右侧视觉：安全星环 */
.hero-grid {
  display: grid;
  grid-template-columns: 1.02fr .98fr;
  align-items: center;
  gap: 40px;
}
.hero-visual {
  position: relative;
  height: 480px;
}
.hv-glow {
  position: absolute;
  inset: 0;
  background: radial-gradient(closest-side, rgba(109, 40, 217, .3), rgba(62, 198, 243, .08) 55%, transparent 75%);
}
.hv-radar {
  position: absolute;
  top: 50%; left: 50%;
  width: 392px;
  aspect-ratio: 1;
  margin: -196px 0 0 -196px;
  border-radius: 50%;
  background: conic-gradient(from 0deg, rgba(62, 198, 243, .2), transparent 28%);
  animation: hv-spin 7s linear infinite;
}
.hv-ring {
  position: absolute;
  top: 50%; left: 50%;
  aspect-ratio: 1;
  border-radius: 50%;
  border: 1px dashed rgba(157, 78, 221, .35);
}
.hv-ring.ring-a { width: 264px; margin: -132px 0 0 -132px; animation: hv-spin 22s linear infinite; }
.hv-ring.ring-b { width: 392px; margin: -196px 0 0 -196px; border-color: rgba(62, 198, 243, .28); animation: hv-spin-rev 38s linear infinite; }
.hv-dot { position: absolute; inset: 0; transform: rotate(var(--a)); }
.hv-dot::before {
  content: "";
  position: absolute;
  top: -4px; left: calc(50% - 4px);
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--purple);
  box-shadow: 0 0 12px var(--purple);
}
.hv-dot.cyan::before { background: var(--cyan); box-shadow: 0 0 12px var(--cyan); }

.hv-core {
  position: absolute;
  top: 50%; left: 50%;
  width: 152px; height: 152px;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: radial-gradient(circle at 35% 28%, rgba(157, 78, 221, .38), rgba(10, 15, 34, .95) 72%);
  border: 1px solid var(--line-strong);
  box-shadow: 0 0 60px rgba(109, 40, 217, .45), inset 0 0 30px rgba(157, 78, 221, .15);
  animation: hv-pulse 3.2s ease-in-out infinite;
}
.hv-core svg { width: 64px; height: 64px; }

.hv-chip {
  position: absolute;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-radius: 999px;
  background: rgba(13, 21, 49, .82);
  border: 1px solid var(--line-strong);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  font-size: 13px;
  color: #d9c8f5;
  letter-spacing: .05em;
  box-shadow: 0 8px 24px rgba(0, 0, 0, .4);
  animation: hv-float 5s ease-in-out infinite;
}
.hv-chip i {
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 8px var(--cyan);
}
.hv-chip.c1 { top: 10%; right: 8%; }
.hv-chip.c2 { top: 40%; right: -2%; animation-delay: 1.2s; }
.hv-chip.c3 { bottom: 12%; right: 18%; animation-delay: 2.2s; }
.hv-chip.c4 { top: 58%; left: -2%; animation-delay: .6s; }

@keyframes hv-spin { to { transform: rotate(360deg); } }
@keyframes hv-spin-rev { to { transform: rotate(-360deg); } }
@keyframes hv-pulse {
  50% { box-shadow: 0 0 92px rgba(109, 40, 217, .68), inset 0 0 36px rgba(157, 78, 221, .25); }
}
@keyframes hv-float { 50% { transform: translateY(-12px); } }

/* 数据条 */
.hero-stats {
  margin-top: 72px;
  position: relative;
  z-index: 1;
  border-top: 1px solid var(--line);
  background: linear-gradient(to bottom, rgba(13, 21, 49, .55), rgba(13, 21, 49, .25));
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}
.hero-stats .wrap {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}
.stat {
  padding: 30px 20px;
  text-align: center;
  border-left: 1px solid var(--line);
}
.stat:first-child { border-left: 0; }
.stat-num {
  font-size: clamp(28px, 3.4vw, 44px);
  font-weight: 900;
  background: var(--grad-text);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  line-height: 1.2;
}
.stat-num small { font-size: .5em; font-weight: 700; margin-left: 2px; }
.stat-label { margin-top: 6px; font-size: 14px; color: var(--dim); letter-spacing: .08em; }

/* ---------- 区块通用 ---------- */
.section { padding: 110px 0; position: relative; }

.sec-head { max-width: 760px; margin-bottom: 56px; }
.sec-head.center { margin-inline: auto; text-align: center; }
.sec-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 13px;
  letter-spacing: .3em;
  color: var(--purple);
  font-weight: 700;
  text-transform: uppercase;
}
.sec-eyebrow::before {
  content: "";
  width: 34px; height: 2px;
  background: var(--grad);
  border-radius: 2px;
}
.sec-head.center .sec-eyebrow::after {
  content: "";
  width: 34px; height: 2px;
  background: var(--grad);
  border-radius: 2px;
}
.sec-title {
  margin-top: 14px;
  font-size: clamp(28px, 3.6vw, 42px);
  font-weight: 900;
  letter-spacing: .02em;
  line-height: 1.25;
}
.sec-desc { margin-top: 16px; color: var(--dim); font-size: 16px; }

/* 玻璃卡片基类 */
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  transition: transform .3s, border-color .3s, box-shadow .3s, background .3s;
}
.card:hover {
  transform: translateY(-6px);
  border-color: var(--line-strong);
  background: var(--card-2);
  box-shadow: 0 18px 44px rgba(2, 4, 12, .5), 0 0 0 1px rgba(157, 78, 221, .08);
}

/* ---------- 计划介绍 ---------- */
.about-grid {
  display: grid;
  grid-template-columns: 1.15fr .85fr;
  gap: 48px;
  align-items: start;
}
.about-text p { color: var(--dim); margin-bottom: 18px; font-size: 16px; }
.about-text p strong { color: var(--text); font-weight: 600; }

.about-pillars {
  margin-top: 28px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}
.pillar {
  padding: 16px 18px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--card);
  font-size: 14.5px;
  display: flex;
  gap: 12px;
  align-items: center;
}
.pillar b { color: var(--text); }
.pillar .dot {
  flex: none;
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--grad);
  box-shadow: 0 0 12px rgba(157, 78, 221, .7);
}

/* 合作双方品牌卡 */
.partner-card {
  padding: 30px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--line);
  background:
    linear-gradient(160deg, rgba(109, 40, 217, .14), rgba(62, 198, 243, .05) 60%, transparent),
    var(--card);
  position: relative;
  overflow: hidden;
}
.partner-card + .partner-card { margin-top: 20px; }
.partner-card::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: var(--grad);
}
.partner-tag {
  font-size: 12px;
  letter-spacing: .22em;
  color: var(--cyan);
  font-weight: 700;
}
.partner-name { margin-top: 8px; font-size: 21px; font-weight: 800; }
.partner-desc { margin-top: 8px; font-size: 14px; color: var(--dim); }

/* 四大特色 */
.feat-grid {
  margin-top: 56px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.feat {
  padding: 30px 26px;
  position: relative;
  overflow: hidden;
}
.feat .no {
  font-size: 15px;
  font-weight: 900;
  letter-spacing: .1em;
  background: var(--grad-text);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.feat h3 { margin-top: 10px; font-size: 21px; font-weight: 800; }
.feat ul { margin-top: 14px; }
.feat li {
  font-size: 14px;
  color: var(--dim);
  padding: 7px 0 7px 18px;
  position: relative;
  border-top: 1px dashed var(--line);
}
.feat li::before {
  content: "";
  position: absolute;
  left: 0; top: 14px;
  width: 7px; height: 7px;
  border-radius: 2px;
  background: var(--grad);
  transform: rotate(45deg);
}

/* ---------- 教材丛书 ---------- */
.books-tabs {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 52px;
}
.tab-btn {
  padding: 10px 22px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--dim);
  font-size: 14.5px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all .28s;
}
.tab-btn:hover { color: var(--text); border-color: var(--line-strong); }
.tab-btn.active {
  background: var(--grad);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 8px 24px rgba(109, 40, 217, .4);
}
.tab-btn .count {
  margin-left: 6px;
  font-size: 12.5px;
  opacity: .8;
}
.books-panel { display: none; }
.books-panel.show { display: block; animation: fadeUp .5s ease both; }
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(18px); }
  to   { opacity: 1; transform: none; }
}

.books-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.book-card {
  display: flex;
  gap: 20px;
  padding: 24px;
  position: relative;
  align-items: flex-start;
}
.book-cover {
  flex: none;
  width: 118px;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 10px 26px rgba(0, 0, 0, .5);
  transition: transform .35s;
}
.book-card:hover .book-cover { transform: scale(1.05) rotate(-1deg); }
.book-info { min-width: 0; }
.book-name { font-size: 17.5px; font-weight: 800; line-height: 1.45; }
.book-meta {
  margin-top: 8px;
  font-size: 13px;
  color: var(--faint);
  line-height: 1.7;
}
.book-meta b { color: var(--dim); font-weight: 600; }
.book-desc {
  margin-top: 10px;
  font-size: 13.5px;
  color: var(--dim);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.book-tags { margin-top: 12px; display: flex; flex-wrap: wrap; gap: 6px; }
.tag {
  font-size: 11.5px;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid var(--line-strong);
  color: #c4a5ec;
  background: rgba(109, 40, 217, .1);
  letter-spacing: .03em;
}
.tag.cyan { border-color: rgba(62, 198, 243, .35); color: #9bdcf5; background: rgba(62, 198, 243, .08); }

/* 书籍封面侧栏：封面 + 详情按钮 */
.book-side {
  flex: none;
  width: 118px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.book-side .btn-detail {
  margin-top: 0;
  width: 100%;
  justify-content: center;
  padding-inline: 10px;
}

/* 书籍详情按钮 */
.btn-detail {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 14px;
  padding: 7px 18px;
  border-radius: 999px;
  border: 1px solid var(--line-strong);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .04em;
  color: #cdb4f5;
  transition: all .25s;
}
.btn-detail svg { width: 14px; height: 14px; }
.btn-detail:hover {
  background: var(--grad);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 6px 18px rgba(109, 40, 217, .4);
  transform: translateY(-2px);
}

/* 出版中角标 */
.badge-wip {
  position: absolute;
  top: 16px; right: 16px;
  font-size: 12px;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 999px;
  color: #0b0f1e;
  background: linear-gradient(120deg, var(--gold), #f3dfa8);
  box-shadow: 0 4px 14px rgba(231, 194, 107, .35);
  letter-spacing: .05em;
}

/* 规划中：系列网格 */
.plan-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}
.plan-card { padding: 24px 22px; }
.plan-card .idx {
  font-size: 13px;
  font-weight: 900;
  letter-spacing: .12em;
  color: var(--faint);
}
.plan-card h3 { margin-top: 8px; font-size: 18px; font-weight: 800; }
.plan-card p { margin-top: 8px; font-size: 13.5px; color: var(--dim); }
.plan-card .bar {
  margin-top: 16px;
  height: 3px;
  border-radius: 3px;
  background: var(--card-2);
  overflow: hidden;
}
.plan-card .bar i {
  display: block;
  height: 100%;
  width: 38%;
  background: var(--grad);
  border-radius: 3px;
}

/* ---------- 编委会 / 顾问团 ---------- */
.role-group { margin-bottom: 48px; }
.role-title {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: .2em;
  color: var(--purple);
  margin-bottom: 22px;
}
.role-title::after {
  content: "";
  flex: 1;
  height: 1px;
  background: linear-gradient(to right, var(--line-strong), transparent);
}
.people-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
/* 人数较少的分组（主任/副主任）居中排列 */
.people-grid.center {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}
.people-grid.center .person { width: 300px; flex: none; }
.person {
  padding: 28px 22px;
  text-align: center;
}
.avatar {
  width: 88px;
  height: 88px;
  margin-inline: auto;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-size: 30px;
  font-weight: 800;
  color: #fff;
  background:
    linear-gradient(var(--bg-raise), var(--bg-raise)) padding-box,
    var(--grad) border-box;
  border: 2px solid transparent;
  box-shadow: 0 8px 24px rgba(109, 40, 217, .3);
  overflow: hidden;
}
.avatar img { width: 100%; height: 100%; object-fit: cover; }
.person-name { margin-top: 16px; font-size: 18px; font-weight: 800; }
.person-role { margin-top: 4px; font-size: 13px; color: var(--cyan); letter-spacing: .04em; }
.person-org  { margin-top: 2px; font-size: 13px; color: var(--faint); }
.person-desc { margin-top: 12px; font-size: 13px; color: var(--dim); line-height: 1.7; }

/* ---------- 配套资源 ---------- */
.res-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
}
.res-item {
  padding: 24px 22px;
  display: flex;
  gap: 16px;
  align-items: flex-start;
}
.res-icon {
  flex: none;
  width: 46px;
  height: 46px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  color: var(--purple);
  background: linear-gradient(150deg, rgba(109, 40, 217, .2), rgba(62, 198, 243, .08));
  border: 1px solid var(--line-strong);
}
.res-icon svg { width: 22px; height: 22px; }
.res-item h3 { font-size: 16.5px; font-weight: 700; }
.res-item p { margin-top: 6px; font-size: 13px; color: var(--dim); line-height: 1.65; }

/* 教材优势 */
.adv-grid {
  margin-top: 56px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.adv {
  padding: 30px 24px;
  position: relative;
  overflow: hidden;
}
.adv::after {
  content: "";
  position: absolute;
  inset: auto -30% -55% -30%;
  height: 120%;
  background: radial-gradient(closest-side, rgba(109, 40, 217, .18), transparent);
  opacity: 0;
  transition: opacity .4s;
}
.adv:hover::after { opacity: 1; }
.adv .no {
  font-size: 30px;
  font-weight: 900;
  background: var(--grad-text);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.adv h3 { margin-top: 8px; font-size: 19px; font-weight: 800; }
.adv p { margin-top: 10px; font-size: 13.5px; color: var(--dim); }

/* ---------- 页脚 ---------- */
.footer {
  border-top: 1px solid var(--line);
  background: linear-gradient(to bottom, rgba(13, 21, 49, .4), var(--bg-deep));
  padding: 64px 0 34px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr;
  gap: 40px;
}
.footer h4 {
  font-size: 14px;
  letter-spacing: .18em;
  color: var(--text);
  margin-bottom: 16px;
  font-weight: 700;
}
.footer p, .footer li { font-size: 13.5px; color: var(--dim); line-height: 2; }
.footer li a:hover { color: var(--purple); }
.footer-brand { display: flex; align-items: center; gap: 12px; font-weight: 800; font-size: 17px; }
.footer-brand .brand-logo { width: 34px; height: 34px; }
.footer-desc { margin-top: 14px; max-width: 380px; }
.copyright {
  margin-top: 48px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  font-size: 12.5px;
  color: var(--faint);
}

/* ---------- 滚动渐入 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity .7s ease, transform .7s ease;
}
.reveal.in { opacity: 1; transform: none; }
.reveal.d1 { transition-delay: .08s; }
.reveal.d2 { transition-delay: .16s; }
.reveal.d3 { transition-delay: .24s; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  * { animation-duration: .01ms !important; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .feat-grid, .adv-grid { grid-template-columns: repeat(2, 1fr); }
  .plan-grid { grid-template-columns: repeat(3, 1fr); }
  .people-grid { grid-template-columns: repeat(3, 1fr); }
  .res-grid { grid-template-columns: repeat(3, 1fr); }
  .books-grid { grid-template-columns: repeat(2, 1fr); }
}

/* Hero 视觉在窄屏隐藏，保持首屏紧凑 */
@media (max-width: 1000px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-visual { display: none; }
}

@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }

  .nav-links {
    position: fixed;
    top: var(--nav-h);
    right: 0;
    width: min(320px, 84vw);
    height: calc(100dvh - var(--nav-h));
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 20px;
    background: rgba(6, 9, 22, .96);
    backdrop-filter: blur(18px);
    -webkit-backdrop-filter: blur(18px);
    border-left: 1px solid var(--line);
    transform: translateX(105%);
    transition: transform .35s ease;
  }
  .nav-links.open { transform: none; }
  .nav-links a { padding: 14px 16px; font-size: 16px; }
  .nav-toggle { display: block; }
}

@media (max-width: 720px) {
  .section { padding: 76px 0; }
  .hero-stats .wrap { grid-template-columns: 1fr 1fr; }
  .stat { border-left: 0; border-top: 1px solid var(--line); padding: 22px 12px; }
  .stat:nth-child(-n+2) { border-top: 0; }
  .books-grid { grid-template-columns: 1fr; }
  .plan-grid { grid-template-columns: repeat(2, 1fr); }
  .people-grid { grid-template-columns: repeat(2, 1fr); }
  .res-grid { grid-template-columns: repeat(2, 1fr); }
  .books-tabs { overflow-x: auto; flex-wrap: nowrap; padding-bottom: 6px; }
  .tab-btn { flex: none; }
}

@media (max-width: 480px) {
  .wrap { width: calc(100% - 36px); }
  .feat-grid, .adv-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .book-card { flex-direction: column; }
  .book-side { width: 150px; }
  .book-cover { width: 100%; }
  .hero-cta .btn { width: 100%; justify-content: center; }
  .brand small { display: none; }
  .people-grid.center .person { width: 100%; }
}